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Optimal scheme for estimating a pure qubit state via local measurements

E. Bagan·M. Baig·R. Munoz-Tapia
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Abstract

We present the optimal scheme for estimating a pure qubit state by means of local measurements on N identical copies. We give explicit examples for low N. For large N, we show that the fidelity saturates the collective measurement bound up to order 1/N. When the signal state lays on a meridian of the Bloch sphere, we show that this can be achieved without classical communication.

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E. Bagan, M. Baig, R. Munoz-Tapia. 2002-11-05. Optimal scheme for estimating a pure qubit state via local measurements. https://doi.org/10.1103/physrevlett.89.277904

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